The present invention relates to a gas turbine engine, and more particularly to a combustion section cooling circuit flow path for a component which receives a cooling airflow therethrough as the external surface thereof are exposed to combustion exhaust gases.
A gas turbine engine includes a compressor section that compresses air then channels the compressed air to a combustor section wherein the compressed airflow is mixed with fuel and ignited to generate high temperature combustion gases. The combustion core gases flow downstream through a turbine section which extracts energy therefrom for powering the compressor section and produce additional output power for driving a fan section.
A turbine stage includes a row of turbine rotor blades secured to the outer perimeter of a rotor disk, with a stationary turbine nozzle, having a plurality of stator vanes disposed adjacent thereto. The combustion gases flow between the stator vanes and the turbine blades to extract energy therefrom and rotate the rotor disk. Since the combustion gases are at a high temperature, the turbine vanes and turbine blades are typically cooled with a portion of compressor air bled from the compressor section.
Typical turbine vanes and blades include an airfoil portion over which the combustion gases flow. The airfoil typically includes one or more serpentine cooling passages or other types of cooling circuits therein through which compressor bleed air is channeled to cool the airfoil. The airfoil may also include various turbulators therein to slow the cooling airflow and increase thermal transfer. The cooling airflow is then discharged from the passages through various film cooling holes disposed through the airfoil outer surface.
High pressure turbine vanes and blades typically have relatively high heat loads at the leading edges. To cool the leading edges, impingement cooling is often utilized. Impingement cooling includes direction of the cooling airflow through a row of crossover holes in a wall between a leading edge cavity and an inner passage of the cooling circuit. The cooling air is then discharged through “showerhead” holes in the leading edge to provide film cooling on an exterior surface of the leading edge of the airfoil. “Gill” holes are also often utilized in specific high temperature areas to provide targeted cooling on these particular areas, however, the diversion of significant cooling airflow may decrease the efficiency of the engine. Furthermore, “gill” holes located in some airfoil areas may undesirably decrease the airfoil effectiveness thus further decreasing engine efficiency.
Accordingly, it is desirable to provide a combustion section cooling circuit flow path for a component which receives a cooling airflow therethrough as an external surface thereof is exposed to a high temperature combustion core gas flow while efficiently utilizing the cooling airflow.